Sous Vide Cooking

I know we have some cooks here, I read that a tight temp control is important to Sous Vide cooking, but 0.1*C, that seems a little tight.

I set up an experimental Sous Vide cooker today. I used a temp controller, >

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and my wife's old, heavy duty deep fat fryer. The temp controller has a 0.3*C differential. I set it for 54.4*C, power turns on at 54.1*C and off at 54.4*C. However after power is off the temp continued to rise to 56.9*C. There's a lot of hot iron in the fryer releasing heat. So I connected a hotplate in series with the fryer, basically lowered the fryer voltage to 52Vac. This was better, the range reduced to 54.1*C to 55.0*C. I will experiment some more with my variac and find the best voltage. I did cook a cheap sirloin tip steak the color was even, but a little more done than I want, but then my temp ran high, so expected. I cooked it for 1-1/2 hours. It was a very thin steak, 5/8" to 3/4", but was evenly red top to bottom. I seared it 30 seconds on each side after Sous Vide. Anyone here tried Sous Vide, your comments?

Mikek

Reply to
amdx
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That sort of tight regulation requires more than simple on-off thermostat operation. You'll need a real PID control. Even some of the low-cost Chinese fridge controllers now have that, like the newer model of my first fermentation temp-control units.

Of course, this begs the question of how they measure the temperature. Forget simple NTCs or diodes, that's not going to be accurate. It would have to be a pricey IC. Otherwise you'll have something that seem to regulate to 54.1-54.4C but in reality it is 55.8-56.1C.

Can't comment there, that's frou-frou stuff to us Wild-West barbecuers :-)

I like steak pink inside but almost black and crunchy on the outside.

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

That would be Ok, after a couple of times cooking you would know, that when it says 54*C you need 52*C, because your system measures low. I think I can get the range limited after a little experimentation with a variac. Here's a picture. >

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Just a bit more done than I wanted. Mikek

Reply to
amdx

.

An "interchangable" NTC thermistor is more expensive than a regular thermis tor, but not much. Back in 1993 we bought Betatherm parts that were interch angeable to 0.2 degree Celcius, and Yellow Spring Instruments sold even tig hter spec parts which were appreciably more expensive.

At the time, integrated circuit temperature sensors were less accurate, and more expensive.

Any of them can be calibrated at a single point - a well stirred ice bath ( with the water being pushed through the bed of ice) is zero degrees Celcius to within about a millidegree Celcius - and will be accurate to close to t hat millidegree over the cooking temperature range.

I've seen more recent ads for more accurate digital parts, but they tend to be noisier and have more self-heating than a good quality thermistor.

You do have to a take care not to dissipate too much power in the thermisto r - I've seen the resistance start to wander around at 1mW. 10uW is conserv ative, and 100uW is probably going to be okay.

Sloman A.W., Buggs P., Molloy J., and Stewart D. ?A microcontroller

-based driver to stabilise the temperature of an optical stage to 1mK in th e range 4C to 38C, using a Peltier heat pump and a thermistor sensor? ? Measurement Science and Technology, 7 1653-64 (1996)

Sloman A. W. ?Comment on ?A versatile thermoelectric temper ature controller with 10 mK reproducibility and 100 mK absolute accuracy? ?? [Rev. Sci. Instrum. 80, 126107 (2009)] ?, Review of Scientif ic Instruments 82, 27101 - 027101-2 (2011)

--
Bill Sloman, Sydney
Reply to
bill.sloman

The exact location of the temp sensor is critical.

--
 Thanks, 
    - Win
Reply to
Winfield Hill

I can't believe that a few degrees (F or C) one way or the other would make that much difference. (This is meat, in a bag, in a water bath, right?) I've never done that. If you wanted to set some average temperature, you could turn the set point down a bit (~1/2 the overshoot) maybe a degree or so.

George H.

Reply to
George Herold

I was thinking it's more like pot roast* which is also nice this time of year. It still get's seared on the outside before going into the pot.

George H.

*or roast beef, If ever in Buffalo, forget chicken wings, have the Beef on Weck, (Kimmelweck) with a good helping of Miller's horseradish.
Reply to
George Herold

I smell "arbitrary precision". :)

A friend loaned me his new (probably overpriced?) Sous Vide appliance. This weekend, I hope to try some salmon via the Sous Vide method.

Reason: Outdoor grill is a PITA to clean. Yeah, I could use foil or planks, but who has time for that? Not to mention my outdoor gas grill is quite old, in general disrepair, and really doesn't cook evenly anymore. (Probably time for a new one.) And cooking fish indoors via other methods can smell up the house, and/or lead to unpredictable results (i.e., microwave).

The truth is that while I'm (more than) a decent cook overall, I'm pretty lazy when it comes to broiled/grilled fish. I have high hopes for this Sous Vide thing. We'll see...

Reply to
mpm

You have to be very cautious with sous vide cooking, since it is a careful balance between "denaturing" proteins and killing pathogens. Get it wrong and some pathogens will thrive.

There is quantitative information on that kind of thing in "Cooking for Geeks: Real Science, Great Cooks, and Good Food" by Jeff Potter The title is pleasingly accurate :)

Reply to
Tom Gardner

It does make a difference - both to the culinary result (different proteins change at different temperatures) and safety (need to kill pathogens).

Reply to
Tom Gardner

and circulation of the water, a common one is a stick you clamp to the side of a pot and it has the heater and a pump inside

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Reply to
Lasse Langwadt Christensen

That's the video that got me stated on this whole thing. Mikek

Reply to
amdx

I never tried sous vide, but a medium-rare steak should be 130-135 F in the center, and I find 135 F to be a little over-done. That's only 2.5 degrees C. In very slow cooking (which sous vide is) the temp of the water is the same as in the center of the meat.

Reply to
Tom Del Rosso

Yes, the wisdom of the internet is 130*F for a rare steak.

We cooked one frozen (then thawed) rib-eye steak last night using sous vide. It had very little red to it. Very disappointed, and not sure if the freezing had anything to do with it or not. The flavor was good it just wasn't rare in appearance, I got the temp regulated very well by using 28 Volts on my fryer, and a temp regulator. My daughter brought her thermometer and they agreed within a tenth or two of a degree F. Cooked it 2 hrs at 130* F. I'll be trying a fresh Rib-eye next time. The second sirloin tip I Sous Vide on Thursday will be seared tomorrow (Monday) just to see how the hold up after 4 days in the fridge.

Mikek

Reply to
amdx

Caution: that isn't high enough to kill all pathogens. For example, according to the FDA, Bacillus Cereus survives at that temperature.

Apparently the FSIS food guidelines state you should - get the food above 136F within a 2hour window - hold it there long enough to pasteurise it - poultry should be 165F

I presume you were using your fryer as a water bath, and keeping the water away from the food. If not, then it isn't actually sous vide.

Reply to
Tom Gardner

I am. Mikek

Reply to
amdx

It might be the frozen part that killed the red color. I like to let my steak warm up for 1-2 hours out of the frig. before I cook it, let the whole thing come up to room temp. I usually crush up a few garlic cloves and smear them on the top(s) as it warms. If you don't want to fire up a grill then pan fry it. I get my case iron 12" skillet nice and hot, with some grease/ fat. (I use bacon fat) Now sear the steak on all it's edges, if it's got a fat side (like a strip steak) then I'll set it on the edge of the pan and let that cook/rend, maybe turn the heat down to 1/2 for this. With all the edges seared, let it cook at lower heat (~1/2) till it's how you like it. (You can sorta tell by poking, I'll cut one open.)

I'm going to make a pot roast tomorrow. :^) George H.

Reply to
George Herold

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